CN100449941C - Application-specific integrated circuit for a low-pass filtering device used for decoupling xDSL channels - Google Patents
Application-specific integrated circuit for a low-pass filtering device used for decoupling xDSL channels Download PDFInfo
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- CN100449941C CN100449941C CNB038126141A CN03812614A CN100449941C CN 100449941 C CN100449941 C CN 100449941C CN B038126141 A CNB038126141 A CN B038126141A CN 03812614 A CN03812614 A CN 03812614A CN 100449941 C CN100449941 C CN 100449941C
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0002—Modulated-carrier systems analog front ends; means for connecting modulators, demodulators or transceivers to a transmission line
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/34—Networks for connecting several sources or loads working on different frequencies or frequency bands, to a common load or source
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
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Abstract
The invention relates to an application-specific integrated circuit (ASIC (305; 306)) for a low-pass filtering device (300) used for decoupling xDSL channels on a telephone line (Li). The inventive integrated circuit is provided with an architecture that is suitable for ASICs (305; 306) such that said ASICs are supplied with energy directly by continuous signals that circulate on the telephone line, whereby each ASIC (305; 306) of the filtering device (300) can comprise an active rectifying circuit (401), a circuit achieving an admittance of the fourth order (402), an impedance-matching circuit (403), and a circuit detecting off-hook/hang-up operations (404).
Description
Technical field
The present invention relates to a kind of is application-specific integrated circuit (ASIC) or the ASIC that makes the low-pass filter of xDSL passage decoupling design.Particularly it is designed to be incorporated in the speech data signal decomposer and transmits on the xDSL passage being used for.The present invention proposes a kind of specific application-specific integrated circuit (ASIC), it especially can improve the selectivity of the filter that wherein is provided with.
Usually, the field of the invention is so-called xDSL field.These technology for example comprise ADSL technology (asynchronous digital subscriber line), VDSL technology (very the High Data Rate numeral is used for line) and HDSL or SDSL technology.By being that example is more specifically described the present invention with ADSL.Yet, also can use other xDSL technology.These technology are implemented in this locality ring of existing telephone network substantially, by on the local ring that constitutes at the network media between telephone office and the subscriber computer.A main purpose of these technology is can transmit various signals simultaneously on the ring of this locality of old telephone network: on the one hand, with the relevant signal of routine call conversation between two users, these first signals comprise signal relevant with voice and letter signal, on the other hand, signal associated with the data, normally the user and can the website of access by internet network between the information of exchange.
Background technology
For transmitting based on these technology, therefore use the copper cash in the house that can reach the user right, formed telephone wire or local loop for a long time, be also referred to as the user of conventional simulation network of POTS (plain old telephone system) or the various telephone sets (being also referred to as narrowband terminal) that are called the conventional digital network of ISDN (integrated service digital network) and be connected to telephone wire.This copper cash is to common twisting and comprise the insulation sheath that polyethylene is made.
This copper cash on the transmission following two kinds of signals:
-in base band, corresponding to the non-modulation analog signal of POTS network, perhaps corresponding to the digital signal of ISDN.If base-band analog signal has 0 to 4kHz frequency usually or considers that letter signal has 0 to 16kHz frequency.The frequency of baseband digital signal from 0 to 94kHz.In practice, base band is used for transmitting at circuit-mode.
-in high frequency band, for example corresponding to other numeral of the information of internet network exchange and signal of modulation.The scope of high frequency band from the telephone baseband to about 1Mhz.In practice, if in the base band of simulation POTS transmission, use copper cash right, then high-band frequency range from 26kHz to 1.1MHz, if it is used for Digital Transmission from 138kHz to 1.1MHz.Usually wish that it is used for permanent transmission,, promptly between user and telephone office, set up persistent communication mainly with group mode.Therefore need not insert the routine operation that carry out under the situation about connecting by switched line, it is a kind of to by using modulator-demodulator, connection software and conduct that switched telephone network constitutes to make the interim method that is connected of the information network of the device that another computer of someone computer and network communicates that this switched line inserts.
Though base band can be used for sending data, particularly preferably with digital regulated demodulator, though and can use high frequency to bring under the situation of the communication that is being called telephone communication on the internet to implement sound communication, but, schematically and for simplifying explain, to consider that base band is used to send first type signal (coming down to word) corresponding to sound communication is arranged, and high frequency band is used to send especially and second type data (coming down to data) seeing Internet's spot correlation.
Base band only can realize low rate (current for being 64Kbit/s under 56Kbit/s and the situation at digital modems under the situation of analog modem), and high frequency band has two-forty (it can near 10Mbit/s).
Therefore the use of so-called ADSL line means that needs will separate as the base band of low frequency from high frequency band.Accompanying drawing 2 schematically shows this separation in local communication loop.This accompanying drawing is depicted as common telephone wire 200 or local loop, and it is made of two copper conductors that line is provided between user 201 with personal device and telephone set 202.
Central authorities' decomposer 205 is incorporated in the decomposer card usually, and this card may comprise nearly tens central decomposers.The function that it has the data-signal that will send towards internet network 204 and separates towards the voice signal that the telephone network 203 of routine sends.Another function of central authorities' decomposer 205 be the voice signal that sends by routine call network 203 and the signal by couple in multiplexer 206 (will be described in more detail below) transmission are carried out multiplexing so that they are transmitted on the twisted-pair feeder 200 of system.In theory, in central decomposer 205, there be low-frequency filter and the high frequency filter that allows respectively by voice signal and ADSL signal.The design of central authorities' decomposer 205 must make the routine call service of POTS and/or isdn network do not disturbed by the appearance of ADSL signal, and makes the data flow of ADSL signal not influenced by the operation (especially off-hook/on-hook operation) of visible some routine on these networks.
Be used for or from the data of internet network 204 by being connected to the DSL couple in multiplexer 206 (being called DSLAM) of central decomposer 205.DSLAM (Digital Subscriber Line Access Multiplexer) is the couple in multiplexer that specialized designs is used for dsl device, is usually located in the telephone office house, and it uses time-division multiplex technology at transmission signals on the internet.
At user's 201 ends, be connected to a decomposer 207 of telephone wire 200 in addition.Decomposer 207 is called as main decomposer.When a large amount of phones was connected to identical line, each all must be subjected to the protection of low-frequency filter in them.In the back in this case, use cheap second order or three rank protecting filters.This filter is easy to make, and compact feature means that they can be called as microfilter.Main decomposer 207 also has the function that the data-signal that will send towards the personal computer related with ADSL Modem 208 and the voice signal that sends towards routine call machine 209 are separated.In theory, in main decomposer 207, also have to be respectively applied for low-frequency filter and the high frequency filter that allows voice signal ADSL signal to pass through.The same with the situation of central decomposer 205, main decomposer 207 also must make its signal for every type can avoid any interference that the signal by other type causes or the phenomenon of adverse effect.
In practice, the low-frequency filter of decomposer is that separate and different with high frequency filter.In this accompanying drawing, only show these filters at user side.High frequency filter 210 (promptly allowing also only to have by data-signal the latter's filter) is set between telephone wire 200 and the DSLAM 206 (phone local side) and between telephone wire 200 and personal computer 208 (user side).High frequency filter 210 partly or entirely is incorporated in the ADSL Modem.Low-frequency filter 211 is arranged between telephone wire 200 and the conventional telephone network 203 (phone local side) and between telephone wire 200 and the routine call machine 209 (user side).
Each filter is used for the equipment that it is connected and wishes to be used for the Signal Spacing of other equipment.Particularly, low-frequency filter 211 is used to prevent that voice signal from being disturbed by data-signal.By the abuse language, this low-frequency filter is also referred to as " decomposer ", because the high pass filter that requires in modulator-demodulator is integrated in this identical modulator-demodulator.This filter is also referred to as micro-filter usually, and it is incorporated in the filter that forms theme of the present invention.
The filter especially installation of low pass filter must satisfy some requirement:
The practiced input and output resistance value of-consideration.For with the power of most probable efficient transmission by the telephone wire transmission, the feature that telephone wire must have is that the impedance in input and output has as far as possible the value near the complex impedance characteristic of telephone wire.In telephone wire, put into filter and must consider this principle.This characteristic impedance is called Zc.In practice, Zc is the value of forcing by standard, and described standard may be different in different countries, even related impedance has suitable substantially value.Therefore, specifically, there be European impedance, Britain's impedance, the German impedance of coordinating and be called 600 ohmages and two U.S.'s impedances of 900 ohmages.Difference between these impedances specifically depends on diameter, insulator and the coil buckling spacing of employed copper cash.
-so-called loss factor or the ILP of inserting, its measures the wasted power of transmission channel when having bridge circuit, filter, equalizer or other circuit.In this case, there is not the situation of filter therein in this factor and is putting into the transmission loss that produces at circuit between the situation of filter by replacing filter measurement; According to various existing standards, when characteristic impedance was a pure resistive, loss must be less than 0.3dB; For complex impedance, inserting loss must be less than 1dB.
-so-called trip loss factor or RLF, it is relevant the measuring of signal power of comparing and returning with the signal power that can transmit.It is represented with following formula:
RLF＝20?log?10?abs(((Zin(w)+Zc(w))/((Zin(w)-Zc(w)))
Wherein Zin (w) measures the input impedance of the device that will measure its RLF, and wherein Zc (w) is the impedance of reference load.Obviously as can be seen, trip loss is corresponding to the impedance measured value.When adaptive perfection (Zin (w)=Zc (w)), it is infinitely great that trip loss is tending towards.In this standard, must be in the trip loss of useful base band (300-400Hz in the POTS network, and in isdn network 300-94000Hz) medium and low frequency filter greater than about 18dB.
In order to attempt to satisfy all these requirements, various types of low-frequency filters have been designed.The elliptic filter that preferred in the prior art a kind of scheme is to use those of ordinary skills to know is also referred to as cauer filter (Cauer filter).Yet, be not satisfied fully on this filter construction.They have following a plurality of defectives and/or unfavorable:
-at first, the structure of elliptic filter is made by passive, non-dissipation parts.The multiple feature of linear characteristic impedance (its imaginary part no longer can be ignored in the ADSL technology) means for obtaining optimum filter need introduce the adjuster that is made of some negative resistance and/or electric capacity.Therefore this adjuster must use the active parts that does not provide in these filters.
-according to the inhibition level of ADSL signal with according to trip loss, the requirement of various standards relates in low-frequency filter will at least four transformers.This has caused following result: on the one hand, and the cost of in making filter, can not ignore, and on the other hand, because the highly variable in ferrite market, having caused sometimes may long poor period.
-owing in the filter of prior art, used a large amount of coils, so the shared space about 15 of each decomposer is to 20cm
2Being installed in this volume of phone local side on the identical card together at many decomposers does not allow in fact to ignore.
-because the performance of the cause passive filter of the tolerance of employed inductance may change between different filters with being different in essence, it is greatly about about 7%.
In order to solve these all problems, the applicant has proposed a kind of low-pass filter, particularly, and on each transmission line of two transmission lines that constitute by telephone wire, the connect integrated circuit of the ASIC type that is provided with of this low-pass filter utilization.On each transmission line, need ASIC is provided so that consider the symmetry of telephone wire.Two ASIC have similar structure, and this structure has formed theme of the present invention.Some passive component still is provided in the low frequency filtering device of incorporating ASIC into.
Accompanying drawing 3 is depicted as can incorporate the accompanying drawing of principle of low frequency filtering device 300 of application-specific integrated circuit (ASIC) that its structure has formed the type of theme of the present invention into.Device 300 has been described it situation of online user A end has been set.Yet it also can be arranged on the phone local side.In this accompanying drawing, can see the telephone wire Li that the routine that is made of first transmission line 301 that is called standard A or line TIP and second transmission line 302 that is called standard B or line RING is arranged.On each transmission line 301 and 302, be respectively arranged with inductance 303 and 304.For the cause of telephone wire symmetry, these two inductance have identical value.Usually, this is worth about 17.5mH (milihenry).On each transmission line, in series be provided with the active parts that is respectively ASIC type 305 and 306 with inductance 303 and 304 respectively.For the cause of telephone wire Li symmetry, two ASIC 305 must have identical structure with 306.
-in low-pass filter 300, the ASIC that is formed with source block is related with passive component.This passive component comprises inductance 303 and 304 particularly.It also can comprise:
-respectively at first electric capacity 310 that is connected two transmission lines 301 and 302 between coil 303 and the ASIC 305 and on the tie point 312 and 314 between coil 304 and the ASIC 306.This first electric capacity 310 makes it can realize the passive component of this device in fact according to the present invention, and this passive component is related with inductance 303 and 304, forms the second order passive filter then.The value of this first electric capacity is generally 27nF.
-on the user A end at second electric capacity 311 that connects in the output of filter 300 respectively in two transmission lines 301 on first transmission line 301 and on the tie point 313 and 315 on second transmission line 302 and 302.Second electric capacity 311 carries out filtering with the HF noise signal of opposing by each ASIC generation in fact.It also has effect to elimination according to the high-frequency signal of xDSL technical transmission.The value of this second electric capacity 311 is 56nF normally.
A key issue of 3 filters of describing is that ASIC must be to its transmission power with reference to the accompanying drawings.Therefore necessarily require to be suitable for making the external power source of their work.Therefore the installation of filter becomes expensive and is restricted.
Summary of the invention
Can address this problem especially according to filtering of the present invention.This is because the present invention proposes a kind of being used for as the application specific architecture at the ASIC as shown in the accompanying drawing 3.A major limitation existing is not need to increase to make the required external power source of ASIC work when the structure of these ASIC of design.Therefore the structure that is proposed provides a solution especially, so that directly provide power to ASIC by the continuous signal in the telephone wire cocycle.
Therefore the present invention relates to a kind of low frequency filtering device in fact, it is installed on the telephone wire that is made of first transmission line and second transmission line, described low frequency filtering device specifically includes source block, this active parts specifically comprises an ASIC and the 2nd ASIC, these two ASIC are identical, the one ASIC in series is arranged on first transmission line between first tie point of first transmission line and second tie point, described first tie point is connected to first pin of an ASIC, second tie point is connected to second pin of an ASIC, the 2nd ASIC in series is arranged on second transmission line between the 3rd tie point of second transmission line and the 4th tie point, described the 3rd tie point is connected to first pin of the 2nd ASIC, the 4th tie point is connected to second pin of the 2nd ASIC, this low frequency filtering device characteristic is that each ASIC is included in the active rectifier circuit that series connection is provided with between first pin of ASIC and second pin, described active rectifier circuit is included among the ASIC, voltage difference be applied to the realization active admittance and be included on the terminal of the electronic circuit among each ASIC, the symbol of this voltage difference is independent of the sense of current that flows in transmission line.
In a specific embodiment, the active admittance of being realized is the quadravalence admittance.
In a specific embodiment, each ASIC comprises that the off-hook/on-hook detection circuit that is arranged in parallel with the active rectifier circuit is to make the electronic circuit short circuit that realizes making active admittance when telephone wire is in hook state.Each ASIC comprises the three-prong that is used for connecting by resistance off-hook/on-hook detection circuit of each ASIC then.
In a specific embodiment, each ASIC comprises the impedance circuit, and this impedance circuit is connected to first pin so that the input impedance of low frequency filtering device is fitted to telephone wire.Each ASIC comprises and is used for the 4th pin that the resistance that is provided with by series connection and electric capacity are connected the impedance circuit that each ASIC is provided with then.
In the particular instance of this embodiment, realize that the electronic circuit of active admittance comprises operation transconductance amplifier, directly by the transmission line power supply, described transmission line is provided with the ASIC under this operation transconductance amplifier to this operation transconductance amplifier.It also can comprise the voltage drop device so that be applied to voltage on the terminal of each operation transconductance amplifier less than the supply voltage of these amplifiers.
Description of drawings
By reading following description and will be better understood the present invention in conjunction with the accompanying drawings and its various application.Said accompanying drawing only is not construed as limiting the invention as an example.In the accompanying drawings:
Accompanying drawing 1 illustrates the expression in the use of ADSL distribution midband as described above;
Accompanying drawing 2 illustrates the low frequency that decomposes on the ADSL line and the principle of high-frequency signal as described above;
Accompanying drawing 3 illustrates the accompanying drawing of low frequency filtering device 300 as described above, and this low frequency filtering device 300 has been incorporated the application-specific integrated circuit (ASIC) that its structure forms the type of theme of the present invention into;
Accompanying drawing 4 is depicted as the accompanying drawing of the main circuit of the structure of using ASIC in low frequency filtering device of the present invention;
The explanation of the interconnection of two ASIC that provide on transmission line is provided accompanying drawing 5;
Accompanying drawing 6 is depicted as a kind of example of the active rectifier embodiment of circuit that belongs to each ASIC;
Accompanying drawing 7 is depicted as a kind of example of the embodiment of single order active admittance;
Accompanying drawing 8 is depicted as a kind of example of the embodiment of the electronic circuit that is provided with and realize the quadravalence active admittance in each ASIC;
Accompanying drawing 9 is depicted as a kind of example of embodiment of the first kind of the OTA that comprises in the quadravalence active admittance;
Accompanying drawing 10 is depicted as a kind of example of embodiment of second type of the OTA that comprises in the quadravalence active admittance;
Accompanying drawing 11 is depicted as a kind of example of the embodiment of the off-hook/on-hook detector circuit that comprises in the integrated circuit in forming theme of the present invention;
Accompanying drawing 12 is depicted as a kind of example of the impedance embodiment of circuit that comprises in the integrated circuit in forming theme of the present invention;
Accompanying drawing 13 is depicted as the whole principle explanation of the integrated circuit that forms theme of the present invention;
Accompanying drawing 14 is depicted as the curve as the active impedance of the inverse of the function representation active admittance of the frequency of processing signals.
Embodiment
Pin L1 and P1 are directly connected to two special electronic circuit of ASIC 305: the circuit and the off-hook/on-hook operation detection circuit 404 that are called active rectifier circuit 401.Therefore these two circuit are installed in the ASIC 305 on first transmission line 301 in parallel.The 3rd electronic circuit as impedance circuit 403 is connected to pin L1.The 4th special electronic circuit 402 in ASIC 305 is to realize that under situation about being discussed active admittance is the circuit 402 of quadravalence admittance.Its value that means the term active admittance depends on the admittance of the frequency of the signal that receives by electronic circuit 402.Electronic circuit 402 is directly connected to active rectifier 401 by first link, 405 and second link 406.
Pin A1 and B1 are connected to impedance circuit 403; Pin C1 is connected to off-hook/on-hook detection circuit 404.Accompanying drawing 5 is depicted as ASIC 305 on transmission line 301 and 302 and 306 setting, also shows the interconnection between these two ASIC.This accompanying drawing shows, except 5 pins that illustrated, also show pin DATA, pin Vpp and pin CK in accompanying drawing 4.The label of the pin of ASIC 305 finishes with index 1, and the label of the pin of ASIC 306 finishes with index 2.
This accompanying drawing shows such fact in fact: pin A1 is connected by the link that comprises electric capacity 501 with A2.Pin B1 is connected by comprising the linking of resistance 502 that is installed in series with electric capacity 503 with B2.Pin C1 is connected by the link that comprises resistance 504 with C2.These passive components act on hereinafter to shown in the description of other accompanying drawing in specify.
Each the effect of four main circuits of ASIC is as follows:
The effect of-active rectifier circuit 401: when telephone wire is in off hook state, direct current DC flows on telephone wire L, but on an ignorant direction in advance, for example, do not know whether the DC electric current is exported or in fact oppositely whether also set up by terminal L1 input and by terminals P 1 about ASIC 305.From hereinafter finding out, realize that the electronic circuit 402 of quadravalence active admittance specifically comprises the correctly amplifier of power supply.Therefore the effect of active rectifier circuit 401 has formed two the voltage V+ and the V-of the sense of current that is independent of on terminal L1 and the P1.For example, if the voltage on terminal L, V (L) greater than going up voltage in terminals P, V (P), then we obtain V+=V (L) and V-=V (P), and if V (L) less than V (P), then we obtain V+=V (P) and V-=V (L).
-realize the function of the circuit 402 of quadravalence admittance: the admittance Y (p) that realizes following form between terminal L that this circuit makes it possible at each ASIC and the P:
Y (p)=1/R0 ((1+a1p+a2p
2+ a3p
3+ a4p
4)/(1+b1p+b2p
2+ b3p
3+ b4p
4)) (equation 1)
Wherein p be with angular frequency w by the related Laplce's variable of equation p=jw, wherein R0 is corresponding to the value in the resistance R 0 shown in the accompanying drawing 7, and wherein other of equation is the constant that hereinafter defines.Admittance is called active admittance, and this is because it is the function of the frequency of the signal that receives by circuit 402.Therefore we obtain:
I (p)=Y (p) V (p) (equation 2)
Wherein V (p) is one terminal L in two ASIC 305 or 306 and the alternating voltage between the P, and I (p) is the electric current that flows in relevant transmission line 301 or 302.
In addition, the circuit that is called the quadravalence active admittance comprises the voltage drop element guaranteeing always to carry voltage V+ and voltage V-to the operational amplifier of the circuit 402 of realizing active admittance, and it is always greater than the amplitude of the voltage that is applied aspect absolute value.
The function of-impedance circuit 403: this circuit makes it possible to change the input impedance of 3 low-frequency filters of describing 300 with reference to the accompanying drawings.Particularly, by the impedance of the type of resistance 502 and electric capacity 503 is provided, between the terminal L1 of ASIC 305 and 306 and L2, can produce negative impedance as the function of the frequency of the various signals that send to ASIC between the terminal B1 of two ASIC 305 and 306 and B2.By selecting the value of this negative impedance carefully, can make the input impedance of low-frequency filter 300 be fitted to telephone wire Li.
The function of off-hook/on-hook detection circuit 404: online when being in on-hook, can obtain low resistance value between terminal L that this circuit makes at each ASIC and the P, about 50 ohm.The quadravalence admittance is then by short circuit.As long as telephone wire is in off-hook, then just appear on the telephone wire, and off-hook/on-hook detection circuit 404 makes it possible to obtain very high impedance at the electric current on the predetermined threshold.
The operator scheme of the various electronic circuits that provide among the ASIC that forms theme of the present invention hereinafter is provided in some particular instance of these embodiment of circuit.
Accompanying drawing 6 is depicted as a kind of example of the embodiment of active rectifier circuit 401.This accompanying drawing shows terminal L and P in ASIC 305 or 306.Circuit 401 comprises four field-effect transistors (FET), two N-channel fet N61 and N62 and two P-channel fet P61 and P62.Terminal L is directly connected to the source electrode of FET P61, the drain electrode of FET N61 and the grid of FET P62 and N62.Terminals P is directly connected to the source electrode of FET P62, the drain electrode of FET N62 and the grid of FET P61 and N61.It is two ends of 601 and 602 that circuit 401 has label; It makes realizing voltage V+ on the point 601 and putting the voltage V-that can realize on 602 less than voltage V+, so therefore is independent of the relative value of voltage V (L) and V (P).Between end 601 and 602, can be the impedance of value Z.In the embodiment of the ASIC that forms theme of the present invention, it is arranged on the quadravalence admittance between end 601 and 602.
A kind of example of the embodiment of the circuit 402 of realization quadravalence admittance is illustrated by accompanying drawing 7,8 and 9.The circuit 402 of realizing the quadravalence admittance is voltage-controlled current sources.The voltage of controlling this current source is that this voltage difference is formed between the end 601 and 602 of circuit 401 in the terminal L of each ASIC and the voltage difference between the terminals P.Active element is used in this circuit: this is OTA (operation transconductance amplifier).Each OTA will be converted to output current i (t) at the voltage difference delta V on its terminal (t) according to following formula:
I (t)=g
mΔ V (t) (equation 3)
The g in equation wherein
mIt is the mutual conductance of OTA.
Before circuit structure that describe to realize the quadravalence admittance, for the sake of simplicity, preferred descriptions realizes the single order admittance, such as at the circuit 700 shown in the accompanying drawing 7.
In this accompanying drawing, circuit 700 has the input 711 of voltage V+ and the output 712 of voltage V-.OTA 701 is characterised in that mutual conductance g1.It has the voltage of the voltage of first input, 702 and second input, 703, the second inputs less than first input 702.Be connected to first input 702 that input 711 conduction link 704 is connected to OTA on the one hand, be connected to capacitor C 11 and be connected to the source electrode of P-slot field-effect transistor 706.The drain electrode of this FET 706 is connected to conduction link 705 by resistance R 0, and this conduction link 705 is connected to output 712.Conduction link 705 is also connected to capacitor C 12, and capacitor C 12 itself is connected to capacitor C 11.
The output of OTA 701 is connected at the tie point that chains 707 that connects two capacitor C 11 and C12.The positive input 708 of operational amplifier 709 also is connected to tie point 707.Second input 703 that the negative input 10 of operational amplifier 709 is connected to OTA 701 is connected in the drain electrode of FET 706 and the link of the tie point 717 between the resistance R 0.At last, the output of operational amplifier 709 is connected to the grid of FET 706.
Consider following equation:
G1=C1/b1 (equation 4)
C11=a1C1/b1 (equation 5)
C12=(1-a1/b1) C1 (equation 6)
Wherein a1, b1 and C1 are the constants that hereinafter defines, by selecting C1 so that the electric current I 1 that flows between link 704 and capacitor C 11 can be ignored the following acquisition of the admittance of circuit 700 with respect to the I2 of the electric current of the source electrode that arrives FET 706:
Y (p)=I (p)/V (p)=(1+a1p)/(R0. (1+b1p)) (equation 16)
Wherein I (p) is to be voltage difference between point 711 and 712 at the electric current and the V (p) of point on 711.
In accompanying drawing 7, two chain-dotted lines 713 define elementary cell 715 with 714 separating on their space.It comprises OTA 701 and two capacitor C 11 and C12 particularly.The part of circuit 700 that is positioned at the right of dotted line 714 has formed the unit 716 that is called terminal units.Terminal units 716 comprises operational amplifier 709, FET 706 and resistance R 0 particularly.
The circuit 402 of realizing the quadravalence admittance is shown in Figure 8.In fact this circuit forms side by side by four elementary cells 715 and terminal units 716.
Therefore each elementary cell comprises OTA 80X, OTA 80X is characterised in that corresponding to the mutual conductance gX of the OTA 701 shown in the accompanying drawing 7, corresponding to the second capacitor C X2 of the capacitor C in accompanying drawing 7 12 with corresponding to the tie point 81X of the tie point in accompanying drawing 7 707, here X from 1 to 4 changes, the numbering of the elementary cell under the expression element.Three the elementary cell JNDs in first elementary cell and other back are that it has for reduction and are applied to the input 711 of circuit 402 and export the voltage drop element 820 of the voltage design of the AC signal between 712.This has guaranteed that various amplifiers always are transferred voltage V+ and voltage V-, and they are always greater than the amplitude of the voltage that imposes on these amplifiers aspect absolute value.Each OTA it just or be directly connected in the link on the voltage V+ 704 on the corresponding negative power end and correspondingly be connected to link 705 on voltage V-.
In order to obtain admittance, promptly as expression in equation 1
Y(p)＝1/R0((1+a1p+a2p
2+a3p
3+a4p
4)/(1+b1p+b2p
2+b3p
3+b4p
4))
Set the various values of electric capacity and mutual conductance as follows:
g1＝C1/b1 (equation?4)
C11＝a1.C1/b1 (equation?5)
C12＝(1-a1/b1).C1 (equation?6)
g2＝b1C2/b2 (equation?7)
C21＝a2.C2/b2 (equation?8)
C22＝(1-a2/b2).C2 (equation?9)
g3＝b2C3/b3 (equation?10)
C31＝a3.C3/b3 (equation?11)
C32＝(1-a3/b3).C3 (equation?12)
g4＝b3C4/b4 (equation?13)
C41＝a4.C4/b4 (equation?14)
C42＝(1-a4/b4).C4 (equation?15)
Wherein C1, C2, C3 and C4 are constants.
In a kind of instantiation of embodiment, the value of selectivity constant as follows:
1/R0＝0.2
a1＝1.64e-4
a2＝1.54e-8
a3＝8.2e-15
a4＝3.56e-19
b1＝1.9e-3
b2＝2.6e-7
b3＝3.9e-12
b4＝3.56e-19
These values make it possible to realize the active impedance as the inverse of active admittance, shown in the curve of accompanying drawing 14.On this curve, as can be seen, near 0 frequency with for the frequency greater than 200kHz, impedance is almost 0, promptly in that it has maximum aspect the absolute value on the frequency values near 30kHz.Therefore suppress level and on frequency, reach maximum, it is hereby ensured separating of low frequency and high-frequency signal near 30kHz.Usually, the maximum impedance value is near 10 kilohms.
Accompanying drawing 9 is depicted as a kind of example of the embodiment of the OTA 801 related with voltage drop element 820.In this accompanying drawing, the positive input in+ of amplifier 801 is directly connected to the grid of P-slot field-effect transistor P901, and the source electrode of this FET is connected to the negative input of amplifier 801.The drain electrode of FETP901 has formed the output of amplifier 801, and promptly it finishes on tie point 811.Also in the drain electrode of FET P901, finish in the link on the voltage V-903.Voltage drop element 820 has made up voltage on the terminal of resistance 900 and the gate source voltage of FET P901 in this case.When voltage was applied to the input of amplifier 801, promptly between in+ and in-, this amplifier class was similar to voltage-controlled current source 902.Current source 902 is formed and is independent of the control voltage drop 820 of temperature ground.Mutual conductance g1 is inversely proportional to the value of resistance 900 haply.
Accompanying drawing 10 is depicted as a kind of example of the embodiment of identical OTA 802,803 and 804.In this accompanying drawing, the positive input in+ of amplifier 80X is directly connected to the grid of a P-slot field-effect transistor P101, and the negative input in-of amplifier 80X is directly connected to the grid of the 2nd P-channel fet P02.The source electrode of these two FET is connected to the conduction link 1000 on voltage V+.The drain electrode of FETP102 is connected to the drain electrode of N-channel fet N102.The grid of this FET N102 is connected to the grid of another N-channel fet N101 on the one hand and is connected to the drain electrode of FET P101 and N101.The source electrode of FET N101 and N102 is connected to the link on voltage V-.When voltage was applied in the input of amplifier 80X, promptly between in+ and in-, amplifier class was similar to voltage-controlled current source 1003.Current source 1003 comprises the internal resistance (not shown) particularly, and it is the clone of the internal resistance of accompanying drawing 9, and therefore this feasible electric current that can limit feed-in can regulate the mutual conductance of each OTA.Mutual conductance g
xAlso depend on characteristics of transistor.
Accompanying drawing 11 is depicted as the example of the embodiment of off-hook/on-hook detection circuit 404.In this accompanying drawing, only show the element of the situation of the polarization that relates to this circuit, this is corresponding to the assigned direction of the electric current in transmission line 301 and 302.Accompanying drawing 11 is included in first basic block 1101 that is provided with among the ASIC 305 and second basic block 1102 that is provided with in ASIC 306.
First basic block 1101 comprises 5 P-slot field-effect transistors.Terminal L1 is directly connected to the source electrode of FET P112, FET P114, FET P113 and the grid of FET P111.Terminals P 1 is directly connected to the source electrode of FET P111, FET P115, the drain electrode of FET P113 and the grid of FET P112.The drain electrode of FET P111 and P112 is connected to a little 1103, and this tie point 1103 is also connected to tie point 1104.Tie point 1104 is also connected to grid and the terminal C1 of FET P113, P114 and P115.At last, terminal C1 is directly connected to the drain electrode of FET P114 and P115.First basic block is double in practice: the complementary basic block (not shown) and the piece 1101 that belong to identical ASIC are installed between terminal L1 and the P1 concurrently.This complementary block was involved in when the sense of current in transmission line 301 and 302 was reverse with respect to above-mentioned definite direction.These two pieces are basic identical except the following fact: all P-channel fets of piece 1101 are replaced by the N-channel fet.The association of these two pieces has formed at the off-hook/on-hook detection circuit shown in the accompanying drawing 4.
The resistance 504 of the value of terminal C1 by having 4.7 megaohms usually is connected to terminal C2.Piece 1102 have with piece 1101 with respect to resistance 504 symmetrical structures that separate them, but replaced except all P-channel fets by the N-channel fet.In ASIC 306, piece 1102 is finished to form off-hook/on-hook detection circuit of ASIC 306, by another complementary block that between terminal L2 and P2, walk abreast and install with second basic block 1102, and have identical structure, but except the N-channel fet has been replaced it by the P-channel fet with piece 1102.
This structure make the electric current that flows by relatively one terminal L in ASIC 305 or 306 and terminals P and in resistance 504 mobile electric current can be from the off-hook pattern to the on-hook pattern detection path.
Accompanying drawing 12 is depicted as a kind of example of the embodiment of impedance circuit 403.This circuit specifically comprises 5 resistance R 101, R102, R103, R104 and R105, operational amplifier 120 and P-channel fet P122.Terminal L is connected to terminal A by resistance R 105, is connected to the positive input 123 of amplifier 120 by resistance R 101, is connected to the negative input 124 of amplifier 120 and the source electrode that is connected to FET P122 by resistance R 102.The negative input 124 of amplifier 120 is connected to link 125 by resistance R 104, and link 125 connects drain electrode and the terminal B of FET P122.The positive input 124 of amplifier 120 is connected to terminal B by resistance R 103.The output of amplifier 120 is connected to the grid of FET P122.
Consider that ASIC 305 is connected by the impedance of value Z with two terminal B of 306, two terminal A of ASIC pass through to be worth the electric capacity connection of C, and the input impedance Zin that obtains from terminal L represents with following formula:
Zin(p)＝Z((R1+R3).C.p+ 1+(R1+R3)/R5)/((R3-R4R1/R2).Cp+1+(R1+R3)/R5) (equation?17)
Wherein Rx is the purpose of reduced equation 17 corresponding to R10x, and x can from 1 to 5 variation.
By adopting following resistance value:
R101=150 kilo-ohm;
R102=100 kilo-ohm;
R103=50 kilo-ohm;
R104=83 kilo-ohm;
R105=450 kilo-ohm;
Equation 17 becomes
Zin(p)＝-2.68Z.((pT+1)/(pT-2.68))
Wherein T is that time constant is so that T=14000C.
Therefore, for the frequency greater than 1/T, impedance circuit 404 is similar to the negative impedance with gain of-2.68.For the frequency less than 1/T, impedance simply equals Z.
Accompanying drawing 13 shows described just now main circuit once more.It also comprises memory module, FIFO memory 132 and and the multiplexer 133 of EEPROM type 131.These different elements are included among each ASIC 305 and 306.Multiplexer 133 is connected to terminal DATA, and terminal CK makes it possible to clock signal is sent to FIFO memory 132, and terminal Vpp is connected to eeprom memory 131.Multiplexer 133 can receive data and transfer data to the latter with multiplexing form from FIFO memory module 132.The FIFO memory can with eeprom memory 131 swap datas.This system makes it possible to have 16 that are used to control to the process of ASIC programming.
First is used for determining at the variable that ASIC programmes is to limit by the content of FIFO memory 132 or by the content of EEPROM 131.Second is used for determining that the admittance that will realize is corresponding to European standard or Unite States Standard.Keep the parameter that 3 positions are used for determining voltage Vdrop, this is equivalent to be adjusted in the resistance R 900 in the accompanying drawing 9, keep the parameter that 6 positions are used for determining various mutual conductances, this is equivalent to be adjusted in the value of the resistance R in that exists in the current source in accompanying drawing 9 and 10, and keeps the parameter that 5 positions are used for determining resistance R 0.
Implement adjusting in known manner by using the simulation multiplexer related to various resistance R 900, Rin and R0 with resistor network.
Claims (8)
1. a low frequency filtering device (300), it is installed on the telephone wire (Li) that is made of first transmission line (301) and second transmission line (302), described low frequency filtering device includes source block, this active parts comprises an ASIC (305) and the 2nd ASIC (306), these two ASIC are identical, the one ASIC (305) in series is arranged on described first transmission line (301) between first tie point (312) of described first transmission line (301) and second tie point (313), described first tie point (312) is connected to first pin (L1) of a described ASIC (305), described second tie point (313) is connected to second pin (P1) of a described ASIC (305), the 2nd ASIC (306) in series is arranged on described second transmission line (302) between the 3rd tie point (314) of described second transmission line (302) and the 4th tie point (315), described the 3rd tie point (314) is connected to first pin (L2) of described the 2nd ASIC (306), described the 4th tie point (315) is connected to second pin (P2) of described the 2nd ASIC (306), and this low frequency filtering device is characterised in that each ASIC (305; 306) be included in described ASIC (305; 306) the described first pin (L1; L2) and the described second pin (P1; P2) the active rectifier circuit (401) that series connection is provided with between, described active rectifier circuit (401) is included in described ASIC (305; 306) in, so that voltage difference is applied to the realization active admittance and is included in each ASIC (305; On the terminal of the electronic circuit 306) (402), the symbol of this voltage difference is independent of at transmission line (301; 302) sense of current that flows in.
2. low frequency filtering device according to claim 1 (300) is characterized in that the admittance that is realized is the quadravalence admittance.
3. low frequency filtering device according to claim 1 (300) is characterized in that each ASIC (305; 306) comprise that off-hook/on-hook detection circuit (404) of being arranged in parallel with active rectifier circuit (401) is to make electronic circuit (402) short circuit that realizes active admittance when being in hook state at telephone wire (Li).
4. low frequency filtering device according to claim 3 (300) is characterized in that each ASIC (305; 306) comprise and be used for connecting each ASIC (305 by resistance (504); Three-prong (the C1 of off-hook/on-hook detection circuit 306) (404); C2).
5. according to each described low frequency filtering device (300) among the claim 1-4, it is characterized in that each ASIC (305; 306) comprise impedance circuit (403), this impedance circuit (403) is connected to the first pin (L1; L2) so that the input impedance of low frequency filtering device (300) is fitted to telephone wire (Li).
6. low frequency filtering device according to claim 5 (300) is characterized in that each ASIC (305; 306) comprise the 4th pin (B1; B2), described the 4th pin (B1; B2) be used for being connected with electric capacity (503) and be arranged on each ASIC (305 by the resistance (502) that series connection is provided with; 306) the impedance circuit (403) in.
7. according to each described low frequency filtering device (300) among the claim 1-4, it is characterized in that realizing that the electronic circuit (402) of active admittance comprises operation transconductance amplifier (801; 802; 803; 804), described operation transconductance amplifier is directly by transmission line (301; 302) power supply is at described transmission line (301; 302) be provided with the affiliated ASIC (305 of this operation transconductance amplifier; 306).
8. low frequency filtering device according to claim 7 (300) is characterized in that realizing that the electronic circuit (402) of active admittance comprises voltage drop device (820) so that be applied to each operation transconductance amplifier (801; 802; 803; 804) voltage on the terminal is less than these amplifiers (801; 802; 803; 804) supply voltage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR02/04295 | 2002-04-05 | ||
| FR0204295A FR2838255B1 (en) | 2002-04-05 | 2002-04-05 | INTEGRATED CIRCUIT WITH SPECIFIC APPLICATION FOR LOW-PASS FILTERING DEVICE FOR DECOUPLING OF XDSL CHANNELS |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1659781A CN1659781A (en) | 2005-08-24 |
| CN100449941C true CN100449941C (en) | 2009-01-07 |
Family
ID=28052159
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB038126141A Expired - Fee Related CN100449941C (en) | 2002-04-05 | 2003-04-07 | Application-specific integrated circuit for a low-pass filtering device used for decoupling xDSL channels |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP1493228B1 (en) |
| CN (1) | CN100449941C (en) |
| AT (1) | ATE410825T1 (en) |
| AU (1) | AU2003240763A1 (en) |
| DE (1) | DE60323956D1 (en) |
| ES (1) | ES2315499T3 (en) |
| FR (1) | FR2838255B1 (en) |
| WO (1) | WO2003085829A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1903674A1 (en) * | 2006-09-22 | 2008-03-26 | Alcatel Lucent | Multiple order low pass filter for an xDSL splitter |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1139996A (en) * | 1994-02-01 | 1997-01-08 | 英国电讯公司 | Filtering |
| US5699421A (en) * | 1995-05-31 | 1997-12-16 | Casio Phonemate, Inc. | Telephone answering device with low cost dual tone multi-frequency detector |
| EP0942578A2 (en) * | 1998-03-12 | 1999-09-15 | Westell Technologies, Inc. | Dual-mode filter for ADSL |
| EP0967735A1 (en) * | 1998-06-26 | 1999-12-29 | Alcatel | Filter arrangement applicable to ADSL splitters |
| EP1005209A2 (en) * | 1998-11-25 | 2000-05-31 | Westell Technologies, Inc. | Signalling method for invoking a test mode in a network interface unit |
| WO2001071980A1 (en) * | 2000-03-20 | 2001-09-27 | Serconet Ltd. | Telephone outlet and system for a local area network over telephone lines |
-
2002
- 2002-04-05 FR FR0204295A patent/FR2838255B1/en not_active Expired - Fee Related
-
2003
- 2003-04-07 AU AU2003240763A patent/AU2003240763A1/en not_active Abandoned
- 2003-04-07 CN CNB038126141A patent/CN100449941C/en not_active Expired - Fee Related
- 2003-04-07 AT AT03730176T patent/ATE410825T1/en not_active IP Right Cessation
- 2003-04-07 WO PCT/EP2003/050093 patent/WO2003085829A1/en not_active Application Discontinuation
- 2003-04-07 EP EP03730176A patent/EP1493228B1/en not_active Expired - Lifetime
- 2003-04-07 ES ES03730176T patent/ES2315499T3/en not_active Expired - Lifetime
- 2003-04-07 DE DE60323956T patent/DE60323956D1/en not_active Expired - Lifetime
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1139996A (en) * | 1994-02-01 | 1997-01-08 | 英国电讯公司 | Filtering |
| US5699421A (en) * | 1995-05-31 | 1997-12-16 | Casio Phonemate, Inc. | Telephone answering device with low cost dual tone multi-frequency detector |
| EP0942578A2 (en) * | 1998-03-12 | 1999-09-15 | Westell Technologies, Inc. | Dual-mode filter for ADSL |
| EP0967735A1 (en) * | 1998-06-26 | 1999-12-29 | Alcatel | Filter arrangement applicable to ADSL splitters |
| EP1005209A2 (en) * | 1998-11-25 | 2000-05-31 | Westell Technologies, Inc. | Signalling method for invoking a test mode in a network interface unit |
| WO2001071980A1 (en) * | 2000-03-20 | 2001-09-27 | Serconet Ltd. | Telephone outlet and system for a local area network over telephone lines |
Also Published As
| Publication number | Publication date |
|---|---|
| ATE410825T1 (en) | 2008-10-15 |
| FR2838255B1 (en) | 2004-06-18 |
| WO2003085829A1 (en) | 2003-10-16 |
| DE60323956D1 (en) | 2008-11-20 |
| CN1659781A (en) | 2005-08-24 |
| EP1493228B1 (en) | 2008-10-08 |
| EP1493228A1 (en) | 2005-01-05 |
| AU2003240763A1 (en) | 2003-10-20 |
| FR2838255A1 (en) | 2003-10-10 |
| ES2315499T3 (en) | 2009-04-01 |
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